Starting mechanism for internal combustion engines



Jan. l, 1935. E. M. AGREN 1,986,459

STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES ATTOQNEY Jan. 1, 1935. E. M, AGREN 1,986,459

STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Feb. l0. 1933 2 Sheets-Sheet 2 INVENToR o BY MW 07m jfl/M M ATTORNEY Patented Jan. l, 1935 "iiruTEo vs'm'liss PATENT OFFICE STARTING MEcnANrsM Fon INTERNAL COMBUSTION ENGINES Ernst g-ren, Stockholm, Sweden, assignor to Pulvls Aktiengesellschaft, Glarus, Switzerland,

a corporation of Switzerland Application February 10,1933, Serial No. 656,192 In Sweden February 19, 1932 1s claims.

Itis already known to veffect the starting `of stationary or mobile internal combustion engines by the aid. of starting mechanisms including an electric starting motorand an electric battery to feed this motor. The object of the present invention is to provide a starting mechanism of the above type in which the risk ofv overloading the battery or subjecting it to heavy loading shocks aswell as the risk of undue stresses on the mechanical power transmission means between the stlarting motor and the engine are entirely avoide With these objects in view the starting mechanism according to the invention includes in addition to the electric starting motor and a starting gear driven by said motor, a clutch automatically responsive to centrifugal force inserted between the electric starting motor and the starting gear which clutch has initial slippage so as to give a smooth connection in starting, and releases on overload but is capable of automatically picking up again when the overload ceases.

In the accompanying drawing two different embodiments of the invention are illustrated in a diagrammatic 'manner in Figs. 1 and 2, respectively. Figs. 3 and 4 show two more constructive embodiments in side elevation, partly in section.

With 'reference to Fig. 1, the numeral 1 indicates the electric starting motor which is fed with current from a storage battery, not shown.

` 2 represents the stationary or mobile internal combustion engine to be started. Mounted on the shaft 3 of the starting motor 1 is the driving vmember '4 `of a slipping clutch, as, for instance,

a clutch'of the design illustrated and described in theU. S. Patent No. 1,830,564 which comprises,4

mainly, a wheel `having wings or blades and a surrounding drum partially filled with a pow- "dered massadapted to serve as power transmit- Ymatically responsive to centrifugal force developed by'rotation of the driving members may be used. In thev embodiment of Fig. l, the shaft 3 carries a wing orA blade wheel 4 keyed to the shaft and surrounded by the drum 5,which is rotatably 'mounted on the shaft 3. The drum 5 carries a pinion 6 which may either be. formed integrally with the drum or rigidly connected thereto. The

' clutch, including the driving member 4 and the drum 5, is axially displaceable along shaft 3 so that the pinion 6 carried by the drum may be moved into and out of engagement with 'a gear wheel 'l mounted on the shaft 8 of the engine 2,

The means for effecting this .displacement may be of various kinds. For instance, the displacement may be performedby means of a lever mechanism either manually or in combination with a pedal or automatically in any well-known manner.

In starting, the clutch and pinion '6 is displaced axially until the pinion is in engagement with gear '7. 'Ihe rotation of shaft 3 by the starting motor 1 causes blades 4 to rotate and to form the' finely divided material contained` in drum@ into drifts ahead of the rotating blades. The increasing centrifugal force resulting from the increase in rate of rotation lof the drifts as the motor comes up to speed tends to pack the particles into solid abutments and causes these abutments to frictionally engage the interior of the drum with gradually increasing force. Consequently, the drum 5, which is connected to the internalcombustionengine through the gears 6 and 7, starts to rotate comparatively gradually and hence the load is gradually applied to the starting motor 1. The clutch also protects the starting motor 1 from an overload. f- A common cause of an overload in a device ofthis type is the backfiring of the internal combustion engine 2 during starting. A backfire causes the shaft 8 to 'suddenly rotate in the reverse direction. This, of course', tends to suddenly reverse the rotation of the startingmotor and to place the parts under high stress. However, before this stress reaches a dangerous value, it causes the drifts to be disrupted and the connection between the engine and the starting motor is thus broken. After the affect of the backfire l has passed, the drifts will be reformed and the starting motor goes on cranking the engine. When the latter starts to rotate under its own power, the clutch is shifted axially so as to disengage pinion 6 from gear 7.

Instead of displacing the slipping clutch in order to bring the gears into mesh for starting, the clutch may be connected to a member which moves only the pinion in order to bring it into mesh with the gear wheel of the engine. In such case, as indicated in Fig. 2, the driving member 4 of the slipping clutch is keyed to the shaft 3 of the starting motor 1, While the driven member of the clutch, that is the drum 5, is formed integrally with or rigidly connected to a screw 9 rotatably surrounding the shaft 3 and engaging a threaded central hole of the pinion 6. 'I'he pinion 6 `of this embodiment will be displaced axially, when the rotation of the screw commences, which takes place as soon as the drum 5 is caused to rotate. Itl t0 be noted that in 'case of a slipping clutch of the type indicated in the drawings, it is possible, by suitable adjustment of the amount of powder, which in the'normal position of the clutch is collected at one place, that is at the lowermost portion of the drum, to cause theblade wheel 4, when the motor 1 is started, to immediately rotate the drum, because at the vei'y starting moment there. is no substantial resistance to the movement of the drum, and no distribution of the powdered mass has yet occurred. This movement of the drum is sufficient to cause the slight displacement of the pinion 6 which is necessary to bring it into a slight mesh with the toothed wheel 7. The engagement of the pinion 6in the toothed wheel 'l is then completed in well-known way and during the starting period the slipping clutch, after the masses of the power motor are also caused to rotate, acts to avoid undue loads or Stresses on the battery and the starting mechanism proper.

The embodiments above described are shown quite diagrammatically.

In Figs. 3 and 4 I have illustrated two more constructional forms of starting devices according to the invention.

In the embodiment shown in Fig. 3 the shaft 3 of the starting motor 1 is formed with screw threads 10 engaging the threaded central bore of the driving clutch member or blade wheel 4, two blades of which are shown at ll, ll. The driven clutch member or drum 5 is formed with a tubular extension 12, freely surrounding the threaded portion of the shaft as well as the hub portion 13 of the starting motor. Said extension 12 is provided with a toothed rim corresponding to the pinion 6 in the embodiments of Figs. 1 and Zand, therefore, also indicated by the reference numeral 6. Said toothed rim 6 is adapted to engage the toothed wheel 7 which is connected in a manner not shown to the motor or engine to be started.

The driving clutch member 4 may be connected to the shaft 3 by a coil spring l5 adapted to prevent the clutch from being acted on by accidental shocks. In starting, the motor 1 rotates the shaft 3 with the screw 10 and, due to its inertia, the driving clutch member 4 does not rotate for a sumcient period to allow the screw to move the clutch yaxially so as to bring the toothed rim 6 into a slight or first mesh with the tooth wheel 7. The resistance exerted by the inertia of the internal combustion engine to be started will then hold the toothed rim 6 and the clutch drum 5 against rotation, thereby causing the clutch to be further moved axially towards the motor 1 until the rim 6 is in full mesh with the toothed wheel 7. The driving clutch member 4 will then gradually cause the drum 5 to rotate through the intermedium of the powdered mass in the way set forth in detail 'in the U. S. Patent No. 1,830,564. In operation, the clutch will act in the way already stated to prevent the transmission of undue stresses or loading shocks to the starting motor and its battery.

After the starting operation has been completed and the engine attains a higher speed than that imparted thereto by the starting device, the toothed wheel will cause the drum 5 to rotate at a higher speed than that of the shaft 3 and the' wing wheel e. Thedrurn will thus become the driving clutch member and after a while it will' cause the blade wheel a to rotate ata higher number of revolutions than the shaft 3. As .a result', the blade wheel .will screw itself back so as to bring pinion 6 out of engagement with the toothed wheel 7.

In Fig. 4 the slipping clutch is shown as used in combination with a Bendix starting device of standard design. The driving clutch member or -blade wheel 4 is keyed to the shaft'3 of the starting motor 1. The driven clutch member or drum 5 is rotatably mounted on the shaft 3 by means of its laterally projectinghub portion 20. This hub portion is connected by a powerful spring 21 to a collar 22 of an externally threaded hollow shaft 23 rotatably surrounding the shaft 3. The threads of said hollow shaft are engaged by an internally threaded pinion 24 which is adapted to be brought into mesh with a toothed rir'n 25 of the flywheel 26 of the engine to be started (not shown). f'

` The operation is much the same as that of the embodiment shown in Fig. 3, the only difference being due to the fact that the drum 5 is not rigidly connected to the screw but connected thereto through the intermedium of the powerful spring 21 which acts to store up power in order to effect a more rapid rotation of the threaded shaft 23 at the starting moment, thereby rendering the starting action more reliable, as is well-known from the Bendix starting device.

The restoring of the pinion to normal out of engagement with the toothed rim 25 takes place in a way which is well-known from the Bendix starting device and does not require any detailed description.

While several embodiments of the present invention have been described, it is to be understood that this has been for purposes of illustration only, and that the scope of the invention is to be limited only by the appended claims.

What I claim is:-

1. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, means automatically responsive to centrifugal force developed by rotation of said armature shaft for coupling said shafts together in such mannerA that said starting motor comparatively gradually assumes the normal starting load and means for uncoupling said shafts when said engine starts.

2. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, means automatically responsive to centrifugal force developed by rotation of said armature shaft for coupling said shafts together in such manner that said starting motor comparatively gradually assumes the normal starting load, said means acting to transmit a limited amount of force so as to provide an overload release, and means for uncoupling said shafts when said engine starts.

3. A starting device for an internal combustion engine having a shaft which requires to Vbe ro tated to start said engine including, in combina.- tion, an electric starting motor having an armature shaft, a clutch comprising a drivingr member mounted on said armature shaft, a driven member rotatably mounted with respect to said driving member, and means for comparatively gradually providing force transmission between said members, said means being automatically responsive to centrifugal force developed by rotation of said driving member, a driven gear on lsaid engine shaft, a driving gear secured to said driven member and adapted to mesh with said driven gear, and means for demeshing said gears when said engine starts.

4. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, ,a clutch comprising a driving member mounted on said armature shaft, a driven member rotatably mounted with respect to said driving member and means forcomparatively gradually providing force transmission between said members, said means being automatically responsive to centrifugalforce developed by rotation of said driving member, a driven gear on said engine shaft, a driving gear secured to said driven member and adapted to mesh with said driven gear, the capacity of said means for providing transmission of force between said members being limited so as to provide an overload release, and means for demeshing said gear when said engine starts.

5. A starting device for an internal combusl tion engine having a shaft which requires to be member mounted on said armature shaft, a

dr'rven member rotatably mounted with respect to said driving member and means automatically responsive to centrifugal force developed by rotation of said armature shaft for coupling said 'members together in such manner that said starting motor comparatively gradually assumes the normal starting load, a driven gear on said engine shaft, a driving gear secured to said driven member and adapted to mesh with said driven gear, and means for demeshing said gears when said engine starts. i

6. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, a clutch having a driving member mounted on said armature shaft, said driving member comprising a plurality of radial blades, a driven rn'ember comprising a drum rotatably mounted on said driving member and forming a space enclosing .said blades and a mass of nely divided material partially fllling said space and adapted to `be packed by centrifugal force resulting from the rotation of said blades into force transmitting abutments for transmitting 'force between said driving and driven members so thatV said starting motor comparativelygradually assumes the normal starting load, a driven gear on said engine shaft, a driving gear secured to said driven member andv adapted to mesh with said-driven gear, and means for demeshing said gears when said engine starts 'l'. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft. a clutch having a driving member mounted on said armature shaft, said driving member comprising a plurality of radial blades,

a driven member comprising a drum rotatably mounted on said driving member and forming a space enclosing said blades and a mass of finely divided material partially filling said space and adapted to be packed bycentrifugal force resulting from the rotation of said blades into force transmitting abutments for transmitting force between said driving and driven members so that said starting motor comparatively gradually assumes the normal starting load, a driven gear on said engine shaft, a driving gear secured to said driven member and adapted to mesh with said driven gear, said abutments being subject to rupture when the force transmitted theremember rotatably mounted with respect to said a driving member a'nd means automatically responsive to centrifugal force developed by rotation of said armature shaft forn coupling said members together in such manner that said startfing motor comparatively gradually 'assumes the normal starting load, a driven gear on said engine shaft, la driving gear secured to said driven member, said driving member being movable in axial direction on said armature shaft, and means for moving sad clutch and driving gear axially on said armature shaft for meshing and demeshing said driving gear with said driven gear.

9. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft formed `with screw threads thereon, a clutch comprising an internally threaded4 driving member carried by said armature shaft so as to be axially displaceable by relative rotation of the armature shaft and the driving member, a driven member rotatably mounted on said driving member and means automatically responsive to centrifugal force developed by rotation of said driving member for coupling said memberstogether in such manner that said starting motor comparatively gradually assumes the normal starting load, a driven gear on said engine shaft, and a driving gear secured to said driven member and adapted to be engaged and disengaged with said driven gear by the axial displacement of said driving member.

10. In a starting device of an internal combustion engine having a shaft, in combination, an electric ,starting motor, having an armature shaft, screw threads formed on said armature shaft, an internally threaded hub member engaging the threads on said armature shaft so as to be axially displaceable by relative rotation of the armature shaft and the hub member, radial blades carried by said hub, a cylindrical drum rotatably mounted on said hub and forming a space enclosing said blades, a mass of finely divided material partially filling said space and adapted to be packed by centrifugal force resulting from the rotation of said blades into force transmitting abutments for transmitting forcefrom said blades to said drum so that said starting motor gradually assumes the normal starting load, a driving gear secured to said drum, andadriven gear mounted on the engine shaftso as to be engaged and disengaged by said driving gear as theilatter internally threaded hub member engaging the threads on said armature shaft so as to be axially displaceable by relative rotation of the armature shaft and the hub member, radial blades carried by said hub, a cylindrical drum rotatably mounted on said hub and forming a space enclosing said blades, a mass of nely divided material partially lling said space and adapted to be packed by centrifugal force resulting from the rotation of said blades into force transmitting abutments for transmitting force from said blades to said drum so that said starting motor gradually asu sumes the normal starting load, said abutments being subject to rupture when the force transmitted therethrough increases to a predetermined value, thereby providing an over-lead release, a driving gear secured to said drinn, and a driven gear-mounted on the engine shaft so as to be engaged and disengaged by said driving gear as the latter is moved axially by axial movement of said hub and drum.

12. A starting device for an internal combu.,n tion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, a clutch including a driving member xed on said armature shaft, a driven member rotatably mounted with respect to said driving member and means automaticallyresponsive to centrifugal force developed by rotation of said armature shaft for coupling said members together in such manner that said starting motor meente comparatively gradually assumes the normal starting load, a driven gear on said engine shaft, an externally threaded member connected to be rotated by said driven member, and an internally threaded driving gear carried by said externally threaded member so as to be axially displaceable by relative rotationof the sleeve and Vthe driving gear for engaging and disengaging said driven gear.

13. A starting device for an internal combustion engine having a shaft which requires to be rotated to start said engine including, in combination, an electric starting motor having an armature shaft, a clutch including a driving member fixed on said armature shaft, a driven.

member rotatably mounted with respect to said driving member and means automatically responsive to centrifugal force developed by rotation of said armature shaft for coupling said members together in such manner that said starting motor comparatively gradually assumes the normal starting load, a driven gear on said engine shaft, an externally threaded sleeve rotatably mounted on said armature shaft, a coil spring having one end secured to said driven member and the other end connected to said sleeve, and an internally threaded driving gear carried by said sleeve so as to be axially displaceable by relative rotation of the sleeve and the driving gear for engaging and disengaging said driven gear.

ERNST M. GREN. 

